Caption: Kuwait oil field fires. A flame tornado snakes across a burning oil lake in the Al-Burgan field, Kuwait. This flame tornado is caused by the complex wind patterns set up by the burning oil wells. The wells of the Al-Burgan field were destroyed toward the end of the 1991 Gulf War by retreating Iraqi troops. Al-Burgan is the second largest oil field in the world, with proven reserves of 60 billion barrels (1 barrel = 159 litres). 365 of its wells were set alight, a total of 600 wells were destroyed throughout Kuwait. Each day some 5 million barrels of oil (800 million litres) are being lost either in flames or by leaking into vast oil lakes.